Lamp Temperature Management Systems and Methods for Liquid Chromatography Analyzers

ABSTRACT

A liquid sample analyzer includes a flow cell, a light source, and a lamp temperature management system. The flow cell is configured to receive a flow of a liquid sample from a liquid sample source. The light source includes a lamp configured to emit light to illuminate the flow of the liquid sample in the flow cell. The lamp temperature management system includes: an air flow generator operable to generate a turbulent air flow to cool the lamp; a thermally conductive primary housing encapsulating the lamp such that a primary air gap is provided between the primary housing and the lamp; and a thermally conductive secondary housing surrounding the primary housing and configured to deflect the turbulent air flow away from the primary housing.

RELATED APPLICATION(S)

The present application claims the benefit of and priority from U.S.Provisional Patent Application No. 61/762,596, filed Feb. 8, 2013, andU.S. Provisional Patent Application Ser. No. 61/713,393, filed Oct. 12,2012, the disclosures of which are incorporated herein by reference intheir entireties.

FIELD

The present technology relates to liquid sample analyzers and lamptemperature management therefor.

BACKGROUND

A deuterium light source is commonly used in liquid chromatography(e.g., LC PDA) applications as an Ultra Violet (UV) light source.Wavelength ranges of down to 190 nm and up to 700 nm are common in thesetypes of applications. Typically, optical intensity varies withtemperature changes and, thus, slight variations in bulb temperature canadversely affect noise and drift in the instrument leading to inaccurateor noisy readings. These types of lamps typically operate at relativelyhigh temperatures (up to 290 deg. C.) and thereby require activecooling. Typically, forced convection by means of a fan is sufficient tokeep the lamp from overheating.

SUMMARY

According to embodiments of the present technology, a liquid sampleanalyzer includes a flow cell, a light source, and a lamp temperaturemanagement system. The flow cell is configured to receive a flow of aliquid sample from a liquid sample source. The light source includes alamp configured to emit light to illuminate the flow of the liquidsample in the flow cell. The lamp temperature management systemincludes: an air flow generator operable to generate a turbulent airflow to cool the lamp; a thermally conductive primary housingencapsulating the lamp such that a primary air gap is provided betweenthe primary housing and the lamp; and a thermally conductive secondaryhousing surrounding the primary housing and configured to deflect theturbulent air flow away from the primary housing.

In some embodiments, the primary housing defines a lamp chambercontaining the lamp and the lamp chamber is fluidly sealed from theexterior of the primary housing.

The liquid sample analyzer may include a buffer chamber defined by andbetween the primary housing and the secondary housing. In someembodiments, the primary housing includes thermal fins extending intothe buffer chamber to facilitate heat transfer from the lamp chamber tothe buffer chamber. In some embodiments, the buffer chamber is fluidlysealed from the turbulent air flow generated by the air flow generator.In some embodiments, the lamp temperature management system isconfigured such that, in use, a laminar air flow is generated in thebuffer chamber.

The liquid sample analyzer may include a feed duct for directing theturbulent air flow at the secondary housing.

In some embodiments, the primary housing includes a window openingfluidly sealed by a transparent lens, and the light source is configuredto emit light from the lamp through the lens to the flow cell. In someembodiments, the liquid sample analyzer includes a mirror disposed inthe primary housing and configured to direct light from the lamp throughthe lens.

According to some embodiments, the liquid sample analyzer includes asource optical fiber configured and operatively connected between theprimary housing and the flow cell to transmit light from the lamp to theflow cell.

In some embodiments, the primary housing and the secondary housing areeach formed of metal.

The lamp may be a deuterium lamp.

In accordance with some embodiments: the primary housing defines a lampchamber containing the lamp and the lamp chamber is fluidly sealed fromthe exterior of the primary housing; a buffer chamber is defined by andbetween the primary housing and the secondary housing; the primaryhousing includes thermal fins extending into the buffer chamber tofacilitate heat transfer from the lamp chamber to the buffer chamber;the buffer chamber is fluidly sealed from the turbulent air flowgenerated by the air flow generator; the lamp temperature managementsystem is configured such that, in use, a laminar air flow is generatedin the buffer chamber; the primary housing includes a window openingfluidly sealed by a transparent lens; and the light source is configuredto emit light from the lamp through the lens to the flow cell.

The liquid sample analyzer may further include a spectrometer opticallyconnected to the flow cell to receive light from the flow cell, and aliquid sample source to supply the flow of the liquid sample to the flowcell.

According to method embodiments of the technology, a method foranalyzing a liquid sample includes providing a liquid sample analyzerincluding: a flow cell configured to receive a flow of a liquid samplefrom a liquid sample source; a light source including a lamp configuredto emit light to illuminate the flow of the liquid sample in the flowcell; and a lamp temperature management system. The lamp temperaturemanagement system includes: an air flow generator operable to generate aturbulent air flow to cool the lamp; a thermally conductive primaryhousing encapsulating the lamp such that a primary air gap is providedbetween the primary housing and the lamp; and a thermally conductivesecondary housing surrounding the primary housing and configured todeflect the turbulent air flow away from the primary housing. The methodfurther includes generating a turbulent air flow using the air flowgenerator and directing the turbulent air flow onto the secondaryhousing to cool the secondary housing, thereby cooling the primaryhousing, and thereby cooling the lamp.

In some embodiments, the primary housing defines a lamp chambercontaining the lamp and the lamp chamber is fluidly sealed from theexterior of the primary housing.

In some embodiments, liquid sample analyzer includes a buffer chamberdefined by and between the primary housing and the secondary housing.

In some embodiments, the primary housing includes thermal fins extendinginto the buffer chamber to facilitate heat transfer from the lampchamber to the buffer chamber.

According to some embodiments, the buffer chamber is fluidly sealed fromthe turbulent air flow generated by the air flow generator.

In some embodiments, the lamp temperature management system isconfigured such that, in use, a laminar air flow is generated in thebuffer chamber.

Further features, advantages and details of the present technology willbe appreciated by those of ordinary skill in the art from a reading ofthe figures and the detailed description of the preferred embodimentsthat follow, such description being merely illustrative of the presenttechnology.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a front perspective view of a liquid sample analyzeraccording to embodiments of the technology.

FIG. 1B is an exploded, front perspective view of the liquid sampleanalyzer of FIG. 1A.

FIG. 2 is a rear perspective view of the liquid sample analyzer of FIG.1A with an outer casing thereof removed.

FIG. 3 is a fragmentary, rear perspective view of the liquid sampleanalyzer of FIG. 1A with the outer casing and a baffle wall thereofremoved.

FIG. 4 is a fragmentary, rear perspective view of the liquid sampleanalyzer of FIG. 1A with the outer casing removed.

FIG. 5 is a cross-sectional view of the liquid sample analyzer of FIG.1A taken along the line 5-5 of FIG. 3.

FIG. 6 is a cross-sectional, perspective view of a light source forminga part of the liquid sample analyzer of FIG. 1A.

FIG. 7 is a front perspective view of the light source of FIG. 6.

FIG. 8 is a rear perspective view of the light source of FIG. 6.

FIG. 9 is a perspective view of a subassembly of the liquid sampleanalyzer of FIG. 1A including a detector, the light source, a flow cellmodule, a base, a carrier tray, a liquid sample source, and a liquidsample receiver.

FIG. 10 is a fragmentary, perspective view of the subassembly of FIG. 9.

FIG. 11 is a further fragmentary, perspective view of the subassembly ofFIG. 9.

FIG. 12 is an exploded, perspective view of a flow cell forming a partof the flow cell module of FIG. 9.

FIG. 13 is a cross-sectional view of the flow cell of FIG. 12.

FIG. 14 is a cross-sectional view of the flow cell of FIG. 12.

DETAILED DESCRIPTION

The present technology now will be described more fully hereinafter withreference to the accompanying drawings, in which illustrativeembodiments of the technology are shown. In the drawings, the relativesizes of regions or features may be exaggerated for clarity. Thistechnology may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the scope of the technology to thoseskilled in the art.

It will be understood that, although the terms first, second, etc, maybe used herein to describe various elements, components, regions, layersand/or sections, these elements, components, regions, layers and/orsections should not be limited by these terms. These terms are only usedto distinguish one element, component, region, layer or section fromanother region, layer or section. Thus, a first element, component,region, layer or section discussed below could be termed a secondelement, component, region, layer or section without departing from theteachings of the present technology.

Spatially relative terms, such as “beneath”, “below”, “lower”, “above”,“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of the device in use or operation in addition to theorientation depicted in the figures. For example, if the device in thefigures is turned over, elements described as “below” or “beneath” otherelements or features would then be oriented “above” the other elementsor features. Thus, the exemplary term “below” can encompass both anorientation of above and below. The device may be otherwise oriented(rotated 90° or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly.

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless expressly stated otherwise. Itwill be further understood that the terms “includes,” “comprises,”“including” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. It will be understood thatwhen an element is referred to as being “connected” or “coupled” toanother element, it can be directly connected or coupled to the otherelement or intervening elements may be present. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

As discussed above, lamps used for illumination in liquid chromatographyare typically actively cooled by forced convection (e.g., by means of afan). A problem with direct forced convection is that turbulent air flowaround the lamp and the lamp enclosure can lead to micro gradients inthe surface temperature of the lamp bulb. These thermal gradients havebeen shown to increase the overall levels of noise produced by the lampand are a detriment to the system.

According to embodiments of the present technology, a lamp temperaturemanagement system and method are provided for cooling a lamp (e.g., adeuterium lamp) of a light source in a spectroscopic liquid analyzersystem. The method and system operate to remove sufficient heat energyfrom the lamp in order to maintain the lamp at a proper temperature,while also reducing the generation of thermal gradients in the surfacetemperature of the lamp bulb and providing higher levels of lampstability.

In accordance with embodiments of the present technology, a liquidsample analyzer includes a light source, including a lamp, and a lamptemperature management system. The lamp temperature management systemincludes a thermally conductive primary housing, a thermally conductivesecondary housing, and an air flow generator. The lamp is mounted in aprimary or lamp chamber of the primary housing with an air gap providedbetween the lamp and the primary housing. This air gap acts as a thermalbuffer and enables laminar convection heat transfer as the primary modeof heat energy removal from the lamp. The secondary housing surroundsthe primary housing, and the secondary and primary housing define asecondary air gap therebetween. The secondary housing serves as abarrier between the primary housing and a system environment surroundingthe secondary housing. According to some embodiments, the lamp chamberis fluidly sealed off from the lamp housing environment (i.e., thesecondary chamber). In some embodiments, the lamp housing includesthermal fins extending outwardly into the surrounding lamp housingenvironment to facilitate thermal transfer to the lamp housingenvironment.

The air flow generator generates a flow of air that passes over theouter surfaces of the secondary housing and may also be circulatedthrough the system environment to cool other components (e.g., otherelectronics). The air flow generator may be a fan or other deviceoperable to force air flow. Heat energy from the lamp environment (i.e.,the lamp chamber) is conducted through the walls of the primary housingand the secondary housing and delivered into the forced convectiveturbulent flow stream of the system environment caused by the air flowgenerator. Because the air in the lamp chamber and the air in thesecondary chamber are mechanically sealed or separated from the forcedair flow, the mechanical energy of the forced air flow is not impartedto the air in the lamp and secondary chambers. Moreover, the secondarychamber serves to provide a more uniformly distributed temperatureprofile or gradient at the outer surfaces of the primary housing. Forexample, while the secondary housing may have relatively cool and hotregions (e.g., with cooler regions being preferentially cooled by theforced air flow as a result of the system configuration), the resultingtemperature gradients may induce a flow (e.g., a laminar flow) of theair in the secondary chamber. This induced air flow may serve toameliorate or flatten the temperature profile at the outer surfaces ofthe primary housing.

By transferring and removing heat energy from the lamp as describedabove, the surface temperature of the lamp can remain very uniformthroughout operation and is unaffected or less affected by slightchanges in external temperature or fan velocity gradients.

Accordingly, the lamp temperature management system of the presenttechnology can cool the lamp and at the same time set up a laminarconvective flow around the primary housing, greatly reducing thermalgradients and leading to higher levels of lamp stability. In addition,the lamp temperature management system can allow for more rapidtemperature stabilization for quick use of the instrument.

With reference to the figures, a liquid sample analyzer 10 including alamp temperature management system 100 according to embodiments of thetechnology is shown therein. The liquid sample analyzer 10 furtherincludes a flow cell module 200 (FIGS. 10-14), a remote radiation orlight source 20, a remote sensing device or detector 30 (FIGS. 1, 9 and10), and a carrier tray 60 affixed to a shared base 12 (FIG. 10). Theanalyzer 10 further includes a remote liquid sample source 50 and aremote liquid sample receiver 52 (FIG. 9). The components 20, 30, 60,100 and 200 are contained in a casing or system housing 170.

The light source 20 (FIGS. 6-8) includes a lamp 22 (FIG. 6) and asuitable power supply to power the lamp 22. The lamp 22 may be a lamp ofany type suitable for spectroscopic analysis. According to someembodiments, the lamp 22 is a deuterium lamp. In some embodiments, thelamp 22 is a deuterium lamp having a wavelength output in the range offrom about 190 nm to 700 nm and a total power output in the range offrom about 25 to 35 watts.

The detector 30 may be any suitable sensing device or detector forspectroscopic analysis. According to some embodiments, the detector 30is a spectrometer including a photodiode array (PDA). The detector 30includes a fiber optic connector 32 for input of optical energy orsignals for further processing.

The liquid sample source 50 may be any suitable source including asupply of the sample to be analyzed in a liquid solvent. According tosome embodiments, the solvent is aqueous. The liquid sample receiver 52may be a waste receptacle or a down line process. According to someembodiments, at least one of the liquid sample source 50 and the liquidsample receiver 52 is provided with a pump to generate a forced flow ofthe liquid sample through the flow cell module 200.

The carrier tray 60 is secured to the base 12 and defines a holdingcavity, socket or slot 64 and a front opening 62 communicating with theslot 64.

The flow cell module 200 (FIGS. 12-14) includes a flow cell unit orassembly 210, a connectorized radiation input or source optical fiber220, a connectorized radiation output or detector optical fiber 230, aliquid sample feed capillary tube 240, a liquid sample exit capillarytube 242, a module housing 250 (FIG. 9), a liquid sample feed connector276, and a liquid sample exit connector 278. The components 210, 220,230, 240, 242, 276, and 278 are mounted in the module housing 250, asdiscussed in more detail herein.

The source connectorized fiber 220 includes a flexible optical fiber orwaveguide 222, a ferrule 224, and a termination 226. The optical fiber222 may be an optical fiber including a solid glass core and a solidglass cladding and may be covered in a protective jacket 223. Theferrule 224 is mounted on one end of the optical fiber 222 such that anoutput end face 222A is exposed adjacent and substantially flush with anend face of the ferrule 224. The termination 226 is mounted on theopposite end of the optical fiber 222 such that an input end face 222Bof the optical fiber 222 is exposed. In use, the termination 226 isinstalled proximate the light source 20 such that light from the lightsource 20 is directed into the optical fiber 222 through the end face222B and transmitted through the fiber 222 and out of the fiber 222through the end face 222A.

The detector connectorized fiber 230 includes a flexible optical fiber232 (which may be covered in a protective jacket), a ferrule 234, and atermination 236. The ferrule 234 is mounted on an end of the opticalfiber 232 such that an input end face 232A is exposed adjacent andsubstantially flush with an input end face of the ferrule 234. Thetermination 236 is mounted on the opposite end of the fiber 232 suchthat an output end face 232B of the fiber 232 is exposed. In use, thetermination 236 is mated with the fiber optic connector 32 of thedetector 30 to transmit light from the end face 232A to the detector 30.

The capillary tubes 240, 242 fluidly couple the flow cell assembly 210to the liquid sample source 50 and the liquid sample receiver 52,respectively, via the connectors 276, 278.

In some embodiments, the flow cell assembly 210 includes a flow cell orliquid core waveguide 212 mounted in or between an entrance “T” memberor joint member 214 and an exit “T” member or joint member 216, whichare in turn mounted in a housing 218. The waveguide 212 may include awaveguide body 215 and a cladding layer 211 extending through thewaveguide body 215. The inner surface of the cladding layer 211 definesa passage or bore 211A extending axially fully through the waveguidebody 215 and terminating at opposed end openings 211B, 211C.

The flow cell assembly 210 includes a fluid feed port 217A fluidlyconnecting the feed tube 240 to the end opening 211B of the waveguidebore 211A and a fluid exit port 217B fluidly connecting the exit tube242 to the end opening 211C of the waveguide bore 211A. The flow cell210 also includes a source fiber receiving bore 217C that receives theferrule 226 and positions the fiber output end face 222A adjacent theend opening 211B, and a detector fiber receiving bore 217D that receivesthe ferrule 234 and positions the fiber end face 232A adjacent the endopening 211C.

The lamp temperature management system 100 includes an inner or primaryhousing 110 (FIG. 3), an outer or secondary housing 130 (FIG. 4), one ormore air flow generators 160, 162 (FIG. 1B) and portions of the systemhousing 170. In the illustrated embodiment, the air flow generatorsinclude an electrically powered fan 160 arranged to draw air into thehousing 170 and an electrically powered fan 162 arranged to exhaust airfrom the housing 170.

The system housing 170 includes a base wall 172 (FIG. 3), opposedsidewalls 174A, 174B, opposed end walls 176A, 176B, a partition wall178, a baffle or top duct wall 180, and an outer casing 190. Thepartition wall 178 defines a first chamber 179A and a second chamber179B. The first chamber 179A contains the light source 20, the innerhousing 110, the outer housing 130, and the fan 160. The detector 30,the carrier tray 60, and the flow cell module 200 are disposed in thesecond chamber 179B. The outer casing 190 and the walls 174A, 174B,176A, 176B collectively fully encase the chambers 179A, 179B.

An intake port 182 is defined in the end wall 176A adjacent the firstchamber 179A. The walls 172, 174A, 178 and 180 define a feed duct 184extending from the intake port 182 to a cross-over or connecting port186 (FIGS. 2 and 4) defined in the partition wall 178. An exhaust port188 is defined in the end wall 176A adjacent the second chamber 179B.

With reference to FIG. 6, the primary housing 110 includes a body 112, alamp holder 116 and a mirror carrier 120 collectively defining a lampchamber 122. The lamp 22 is disposed in the lamp chamber 122.

The body 112 includes an integral base 112A (secured to the base 12), alamp access opening 112B, a mirror opening 112C, and a window opening124. A plurality of integral cooling fins 118 extend radially outwardlyfrom the body 112 and define a plurality of substantially parallelcooling channels 118A therebetween.

The lamp holder 116 is removeably secured (e.g., by screw threads) inthe lamp access opening 112B to seal the opening 112B. The lamp holder116 may include an electrical connection for supplying electrical powerto the lamp 22.

The mirror carrier 120 is slideably mounted at the mirror opening 112Cto seal the opening 112C. A mirror 121 is mounted on the mirror carrier120 for movement therewith. A mirror positioning mechanism 120Aincluding adjustment knobs 120B is provided to translate the mirror 121along each of an X axis and a Y axis relative to the lamp chamber 122.According to some embodiments, the mirror 121 is a concave mirrorconfigured to focus and direct light from the lamp 22 through the windowopening 124. A lens 124A is provided in the window opening 124 to sealthe window opening 124 and in some embodiments to focus the light beamfrom the mirror 121. An alignment block 124B may be provided to receiveand positively align the termination 226 of the flow cell assembly 210with the window 124.

The body 112 and the fins 118 are formed of a thermally conductivematerial. According to some embodiments, the body 112 and the fins 118are formed of a material having a thermal conductivity in the range offrom about 100 W/m-k to 250 W/m-k. In some embodiments, the body 112 andthe fins 118 are formed of metal, and in some embodiments, aluminum.According to some embodiments, the body 112 and the fins 118 constitutea monolithic structure. In some embodiments, the lamp holder 116 and themirror carrier 120 are likewise formed of a thermally conductivematerial and in some embodiments, a metal (e.g., aluminum).

With the exception of the region of engagement between the lamp 22 andthe lamp holder 116, the lamp 22 is surrounded by an air gap G1 (FIG. 6)between the outer surface of the lamp 22 and the inner surface of theinner housing 110. According to some embodiments, the air gap G1 has awidth W1 (FIG. 6) of at least 0.05 inch and, in some embodiments, in therange of from about 0.1 to 0.125 inch.

The secondary housing 130 (FIGS. 3-5) includes a top wall 132, a bottomwall 133, a front wall 134, a rear wall 135, an outer sidewall 136, andan inner sidewall 137. The bottom wall 132 may be a section of the basewall 172, the sidewall 136 may be a section of the sidewall 174A, andsidewall 137 may be a section of the partition wall 178. The secondaryhousing 130 defines a buffer chamber 140. A reduced height plenum 142 isdefined between the top wall 132 and the top wall 180 and fluidlyconnects the feed duct 184 and the connecting port 186.

With the exception of the region of engagement between the base 112B andthe base 12, the primary housing 110 is surrounded by an air gap G2.According to some embodiments, the air gap G2 has a width W2 of at leastabout 0.25 inch, and, in some embodiments, in the range of from about0.5 to 1.5 inch. As shown, the outer housing 130 may be substantiallybox shaped. However, other configurations may be employed.

The outer housing 130 is formed of a thermally conductive material.According to some embodiments, the outer housing 130 is formed of amaterial as described above for the inner housing 110.

In use, as discussed below, the lamp 22 is powered to generate a lightbeam that is directed into the flow cell assembly 210 to enablespectroscopic analysis. In doing so, the lamp 22 generates excessiveheat that must be removed to ensure proper operation of the lamp 22. Tothis end, the fan 160 and the fan 162 draw a flow F1 (FIG. 3) of airinto the intake port 182 and generates a forced flow F2 of the airthrough the feed duct 184 toward the outer housing 130. According tosome embodiments, the flow F2 has a volumetric flow rate in the range offrom about 10 to 15 cubic feet per minute. The circulated air flows F3(FIG. 4) over the outer housing 130, through the connecting port 186(flow F4), through the chamber 179B (flow F5), and out through theexhaust port 188 (flow F6). The turbulent air flow is thus isolated ordeflected away from the inner housing 110. The turbulent forcedcirculated air removes heat from and thereby cools the outer housing130. Heat energy from the lamp 22 is, sequentially, transferred throughthe air gap G1 (in some embodiments, primarily by a laminar convectiveair flow F7 (FIG. 6)), conductively transferred through the innerhousing 110, transferred through the air gap G2 (in some embodiments,primarily via a laminar convective air flow F8 (FIG. 5)), conductivelytransferred through the outer housing 130 and transferred into theforced convective turbulent air flow stream (F3) of the circulated air.

According to some embodiments and as shown, the lamp chamber 122 (i.e.,the lamp environment) is substantially fully fluidly sealed from thebuffer chamber 140. According to some embodiments, the buffer chamber140 is also substantially fully fluidly sealed from the forced air flow(i.e., the system environment). In other embodiments, the buffer chamber140 may be fluidly connected to the system environment, but configuredsuch that turbulence from the forced air flow is substantially preventedor inhibited from introducing turbulence into the air in the bufferchamber 140. The air gap G1 acts as a thermal buffer and allows laminarconvective heat transfer as the primary mode of heat energy removal fromthe lamp 22. Likewise, the air gap G2 may act as a thermal buffer andallow laminar convective heat transfer as the primary mode of heatremoval from the inner housing 110. The fins 118 facilitate the thermalheat transfer to the buffer environment by increasing the total surfacearea and thereby increasing the rate of heat transfer. By transferringand removing heat from the lamp 22 in this way, the surface temperatureof the lamp 22 can be maintained more spatially uniform throughoutoperation and will tend not to be affected by slight changes in externaltemperature or fan velocity gradients.

Because the lamp chamber 122 is sealed off from the system environmentand the air circulated by the fans 160, 162, fresh air is prevented fromentering the lamp chamber 122. In this way, the lamp temperaturemanagement system 100 can limit or reduce the generation of ozone in thelamp environment by the lamp 22. In general, ozone tends to absorb UVlight and can thereby alter the intensity of the light emitted from thelight source 20, and thereby create undesirable noise.

In order to achieve the foregoing benefits, a heat balance may beestablished from the lamp surface through to the system environment withconsideration of system geometry and materials. The heat balance andoperation may be dependent on the widths of the air gaps G1, G2, themasses of the housings 110, 130, the quantity and sizes of the fins 118,the volumes of air contained in the chambers 122, 140, the thicknessesof the walls of the housings 110, 130, and the air flow velocity of theair flow F3.

In an exemplary use, a flow of the liquid sample is pumped or otherwisedriven from the liquid sample source 50, through the feed connector 276,through the feed tube 240, through the waveguide 212 (more particularlythrough the waveguide bore 211A from the end opening 211B to the endopening 211C), through the exit tube 242, and through the exit connector278 to the liquid sample receiver 52.

Simultaneously, a beam of optical energy emitted from the lamp 22 of thesource 20 is transmitted, in sequence, through the window 124, into theinput fiber 222 through the end face 222A, through the fiber 222, intothe waveguide bore 211A through the fiber end face 222B, through theliquid sample in the bore 211A, into the exit fiber 232 through the endface 232A, and through the fiber 232 to the input of the detector 30through the fiber end face 232B. The liquid sample in the bore 211Aserves as an optical core and the cladding layer 211 serves as anoptical cladding providing total internal reflection. The waveguide 212has an illuminated path length LP (i.e., the axial length of the columnof liquid sample illuminated in the bore 211A) extending from the fiberend face 222A to the fiber end face 232A.

In an exemplary embodiment, the detector 30 is a PDA spectrometerincluding a photodiode array and a grating to divide an incident lightbeam into prescribed wave lengths (or ranges of wave lengths) andproject the different wave lengths onto different respective photodiodesof the PDA. The liquid sample is axially illuminated by the source beamfrom the source 20. The illuminated liquid sample will absorb andthereby attenuate the light at different wave lengths in accordance withits composition. The voltage of each photodiode will be reduced inproportion to the reduction of its corresponding wave length in thelight beam exiting the liquid sample through the optical fiber 232.

Many alterations and modifications may be made by those having ordinaryskill in the art, given the benefit of present disclosure, withoutdeparting from the spirit and scope of the invention. Therefore, it mustbe understood that the illustrated embodiments have been set forth onlyfor the purposes of example, and that it should not be taken as limitingthe invention as defined by the following claims. The following claims,therefore, are to be read to include not only the combination ofelements which are literally set forth but all equivalent elements forperforming substantially the same function in substantially the same wayto obtain substantially the same result. The claims are thus to beunderstood to include what is specifically illustrated and describedabove, what is conceptually equivalent, and also what incorporates theessential idea of the invention.

What is claimed:
 1. A liquid sample analyzer comprising: a flow cellconfigured to receive a flow of a liquid sample from a liquid samplesource; a light source including a lamp configured to emit light toilluminate the flow of the liquid sample in the flow cell; and a lamptemperature management system including: an air flow generator operableto generate a turbulent air flow to cool the lamp; a thermallyconductive primary housing encapsulating the lamp such that a primaryair gap is provided between the primary housing and the lamp; and athermally conductive secondary housing surrounding the primary housingand configured to deflect the turbulent air flow away from the primaryhousing.
 2. The liquid sample analyzer of claim 1 wherein the primaryhousing defines a lamp chamber containing the lamp and the lamp chamberis fluidly sealed from the exterior of the primary housing.
 3. Theliquid sample analyzer of claim 1 including a buffer chamber defined byand between the primary housing and the secondary housing.
 4. The liquidsample analyzer of claim 3 wherein the primary housing includes thermalfins extending into the buffer chamber to facilitate heat transfer fromthe lamp chamber to the buffer chamber.
 5. The liquid sample analyzer ofclaim 3 wherein the buffer chamber is fluidly sealed from the turbulentair flow generated by the air flow generator.
 6. The liquid sampleanalyzer of claim 3 wherein the lamp temperature management system isconfigured such that, in use, a laminar air flow is generated in thebuffer chamber.
 7. The liquid sample analyzer of claim 1 including afeed duct for directing the turbulent air flow at the secondary housing.8. The liquid sample analyzer of claim 1 wherein: the primary housingincludes a window opening fluidly sealed by a transparent lens; and thelight source is configured to emit light from the lamp through the lensto the flow cell.
 9. The liquid sample analyzer of claim 8 including amirror disposed in the primary housing and configured to direct lightfrom the lamp through the lens.
 10. The liquid sample analyzer of claim1 including a source optical fiber configured and operatively connectedbetween the primary housing and the flow cell to transmit light from thelamp to the flow cell.
 11. The liquid sample analyzer of claim 1 whereinthe primary housing and the secondary housing are each formed of metal.12. The liquid sample analyzer of claim 1 wherein the lamp is adeuterium lamp.
 13. The liquid sample analyzer of claim 1 wherein: theprimary housing defines a lamp chamber containing the lamp and the lampchamber is fluidly sealed from the exterior of the primary housing; abuffer chamber is defined by and between the primary housing and thesecondary housing; the primary housing includes thermal fins extendinginto the buffer chamber to facilitate heat transfer from the lampchamber to the buffer chamber; the buffer chamber is fluidly sealed fromthe turbulent air flow generated by the air flow generator; the lamptemperature management system is configured such that, in use, a laminarair flow is generated in the buffer chamber; the primary housingincludes a window opening fluidly sealed by a transparent lens; and thelight source is configured to emit light from the lamp through the lensto the flow cell.
 14. The liquid sample analyzer of claim 1 furtherincluding: a spectrometer optically connected to the flow cell toreceive light from the flow cell; and a liquid sample source to supplythe flow of the liquid sample to the flow cell.
 15. A method foranalyzing a liquid sample, the method comprising: providing a liquidsample analyzer including: a flow cell configured to receive a flow of aliquid sample from a liquid sample source; a light source including alamp configured to emit light to illuminate the flow of the liquidsample in the flow cell; and a lamp temperature management systemincluding: an air flow generator operable to generate a turbulent airflow to cool the lamp; a thermally conductive primary housingencapsulating the lamp such that a primary air gap is provided betweenthe primary housing and the lamp; and a thermally conductive secondaryhousing surrounding the primary housing and configured to deflect theturbulent air flow away from the primary housing; using the air flowgenerator, generating a turbulent air flow and directing the turbulentair flow onto the secondary housing to cool the secondary housing,thereby cooling the primary housing, and thereby cooling the lamp. 16.The method of claim 15 wherein the primary housing defines a lampchamber containing the lamp and the lamp chamber is fluidly sealed fromthe exterior of the primary housing.
 17. The method of claim 15 whereinthe liquid sample analyzer includes a buffer chamber defined by andbetween the primary housing and the secondary housing.
 18. The method ofclaim 17 wherein the primary housing includes thermal fins extendinginto the buffer chamber to facilitate heat transfer from the lampchamber to the buffer chamber.
 19. The method of claim 17 wherein thebuffer chamber is fluidly sealed from the turbulent air flow generatedby the air flow generator.
 20. The method of claim 17 wherein the lamptemperature management system is configured such that, in use, a laminarair flow is generated in the buffer chamber.